<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"> 
<title>CSS基本语法</title> 
<style>
p{
    line-height: 2px
}
p.hidden{
    visibility:hidden;
}
</style>
</head>

<body>
    <p>这一行正常显示</p>
    <p class="hidden">这一行被隐藏</p>
    <p>注意，隐藏的行实际还是占用空间</p>
</body>
</html>